MULTIVARIATE ANALYSIS OF PEOPLE'S KNOWLEDGE AND OPINIONS ON ORGAN DONATION AND TRANSPLANTATION IN THE PHILIPPINES

BY : OLIVIA TUBIG SISON (APRIL 2008)

ABSTRACT :

ANALYSIS OF DATA WITH NUMEROUS OBSERVATIONS OR VARIABLES ALSO KNOWN AS "MULTIVARIATE" IS PART OF MOST RESEARCH. DATA REDUCTION TECHNIQUES SIMPLIFY THE ANALYSIS OF MULTIVARIATE DATA AND PLAY AN IMPORTANT COMPLEMENTARY ROLE WITH OTHER MULTIVARIATE TECHNIQUES SUCH AS MULTIPLE LOGISTIC REGRESSION ANALYSIS THROUGH BOTH DATA SUMMARIZATION AND DATA REDUCTION. THE PROBLEM ASSOCIATED WITH LARGE NUMBERS OF VARIABLES OR HIGH INTER CORRELATIONS AMONG VARIABLES CAN SUBSTANTIALLY BE REDUCED BY SUBSTITUTION OF THE NEW VARIABLES IN SUBSEQUENT ANALYSIS. THE AIM OF CONDUCTING THIS STUDY WAS TO COMPARE THE PERFORMANCE OF USE AND NON-USE OF DATA REDUCTION TECHNIQUES IN DETERMINING THE FACTORS ASSOCIATED WITH WILLINGNESS OF FILIPINO PEOPLE TO DONATE AN ORGAN.

USING CROSS SECTIONAL DATA FROM THE NATIONWIDE SURVEY ON THE PEOPLE'S KNOWLEDGE AND OPINIONS ABOUT ORGAN DONATION : A FOLLOW SURVEY CONDUCTED BY THE INSTITUTE OF CLINICAL EPIDEMIOLOGY, UP MANILA FOR THE RENAL DISEASE CONTROL PROGRAM (REDCOP) OF THE NATIONAL KIDNEY AN TRANSPLANT INSTITUTE (NKTI), THIS STUDY ASSESSED THE PERFORMANCE OF TWO LOGISTIC MODELS USING THE ORIGINAL VARIABLES (MODEL 1) AND REDUCED VARIABLES (MODEL 2) IN DETERMINING FACTORS ASSOCIATED WITH WILLINGNESS OF FILIPINO PEOPLE TO DONATE AN ORGAN. PRINCIPAL COMPONENTS AND FACTOR ANALYSIS WERE EMPLOYED TO REDUCE THE DIMENSIONALITY OF THE ASSET OWNERSHIP AND OPINION ITEM VARIABLES, RESPECTIVELY. TO COMPARE THE TWO LOGISTICS MODELS, GOODNESS-OF-FIT TESTS USING PEARSON CHI SQUARE AND HOSMER AND LEMESHOW, AND AREA UNDER THE RECEIVER OPERATING CHARACTERISTIC (ROC) CURVES WERE USED.TO VALIDATE THE FITTED MODEL, THE SENSITIVITY, SPECIFICITY, AND CORRECT CLASSIFICATION RATES FROM CLASSIFICATION TABLES, AS WELL AS AREA UNDER THE ROC CURVES WERE OBTAINED FOR BOTH THE ORIGINAL AND SAMPLED DATA SHEET.

RESULTS SHOWED THAT MODEL 2 DID NOT FIT THE DATA. ON THE OTHER HAND, MODEL 1, THE LOGISTIC MODEL WITH PREDICTORS THAT INCLUDED REDUCED VARIABLES DERIVED FROM USING THE PRINCIPAL COMPONENTS AND FACTOR ANALYSIS HAD A GOOD FIT WITH AN ESTIMATED OVER ALL RATE OF CORRECT CLASSIFICATION OF 65.6% AND THE SENSITIVITY AND SPECIFICITY WERE 65.9% AND 62.3% RESPECTIVELY. VALIDATING THE FITTED METHOD USING A SAMPLED DATA FROM THE TEST DATA AND VALIDATION DATA SETS WERE ALMOST SIMILAR WITH A 7% DIFFERENCE IN THE SPECIFICITY VALUES. THE AREA UNDER THE ROC CURVE OF THE TEST AND VALIDATION DATA SETS WAS NOT SIGNIFICANTLY DIFFERENT AT 5% LEVEL OF SIGNIFICANCE (P-VALUE=0.36). THE FACTORS THAT WERE FOUND TO BE ASSOCIATED WITH WILLINGNESS OF PEOPLE TO DONATE AN ORGAN WERE UNDERSTANDING OF ORGAN DONATION, EDUCATIONAL ATTAINMENT, FACTOR 1 ( OPINIONS ON WHAT WILL HAPPEN TO THE DONOR, SPECIFICALLY TO THE BODY), FACTOR 2 (RIGHTS OF DONORS AND RECIPIENTS IN ORGAN DONATION AND TRANSPLANTATION PROCESS), FACTOR 3 (OPINIONS ON EXTERNAL FACTORS SUCH AS CAPABILITY OF DOCTORS AND SURVIVAL OF ORGAN RECIPIENTS), FACTOR 4 (ALTRUISM), AND FACTOR 5 ( OPINION ON DISFIGUREMENT OF BODY AND BANNING OF ORGAN DONATION TO FOREIGNERS).

THE LOGISTIC REGRESSION MODEL THAT INCLUDED THE REDUCED VARIABLES DERIVED FROM THE DATA REDUCTION TECHNIQUES PROVIDED A GOOD FITTED AND VALID MODEL. THIS MODEL MAYBE UTILIZED FOR FUTURE IDENTIFICATION OF PEOPLE WHO WILL BE WILLING TO DONATE AN ORGAN.